Chapter 3: Problem 36
Find the maximum or minimum value of the function. $$f(t)=10 t^{2}+40 t+113$$
Short Answer
Expert verified
The minimum value of the function is 73.
Step by step solution
01
Identify the Quadratic Function
The function given is a quadratic function in the form of \( f(t) = at^2 + bt + c \), where \( a = 10 \), \( b = 40 \), and \( c = 113 \). In this case, \( a \) is positive, which means the parabola opens upwards, indicating a minimum value point at its vertex.
02
Find the Vertex of the Parabola
Use the vertex formula for a quadratic function, which is \( t = \frac{-b}{2a} \). Substitute \( a = 10 \) and \( b = 40 \) into the formula to find the \( t \)-coordinate of the vertex. This results in \( t = \frac{-40}{2(10)} = -2 \).
03
Calculate the Function Value at the Vertex
Substitute \( t = -2 \) back into the original function to find \( f(-2) \). Compute \( f(-2) = 10(-2)^2 + 40(-2) + 113 = 40 - 80 + 113 = 73 \).
04
Determine the Minimum Value
Since the parabola opens upwards and the vertex \( t = -2 \) gives \( f(t) = 73 \), the minimum value of the function is \( 73 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Vertex Formula
The vertex formula is a crucial tool for working with quadratic functions. It helps us find the vertex, which is the highest or lowest point on a parabola, depending on whether it opens upwards or downwards. For any quadratic function in the standard form \( f(t) = at^2 + bt + c \):
- The vertex \( t \)-coordinate can be found using the formula \( t = \frac{-b}{2a} \).
- This formula derives from the process of completing the square and highlights the symmetrical nature of parabolas around their vertex.
- Substituting the coefficients \( a \) and \( b \) from our quadratic equation, you can efficiently find this \( t \)-value, allowing further evaluation or graphing of the quadratic.
Parabola
A parabola is a curved, U-shaped graph formed by plotting a quadratic equation. Parabolas appear naturally in many real-world scenarios, such as the path of projectiles. The shape of the parabola provides important features:
- It has an axis of symmetry, which runs through the vertex.
- The direction in which the parabola opens is determined by the sign of the \( a \)-coefficient: positive opens upwards, negative opens downwards.
- The vertex of the parabola is the turning point, either a maximum or minimum value.
Minimum Value
In a quadratic function where the parabola opens upwards (which happens if \( a > 0 \)), the vertex represents the minimum point. To find the minimum value of the function:
- Use the vertex formula to obtain the \( t \)-coordinate of the vertex.
- Substitute this \( t \)-value back into the original quadratic equation.
- The resulting \( f(t) \) value is the minimum value of the function.
Quadratic Equations
Quadratic equations are polynomials of degree two, having the general form \( ax^2 + bx + c = 0 \). The characteristics of quadratic equations include:
- A parabolic graph, which can be identified readily due to its distinctive U-shape.
- The potential to have zero, one, or two real roots based upon the discriminant \( b^2 - 4ac \).
- Always includes a maximum or minimum value at its vertex.
- Can be solved using methods like factoring, completing the square, or the quadratic formula.